Measuring and controlling apparatus



Feb. 22, 1944. F, LUHRS 2,342,413

MEASURING AND CONTROLLING APPARATUS Filed Dec. 20, 1958 5 Sheets-Sheet l INVENTOR JOHN F. LUHRS Feb. 2z, 1944. J, F LUHRS k3,422,413

MEASURING AND CONTROLLING APPARATUS Filed nec. 2o,` 195s 5 sheets-sheet 2 Fla. 3

INVENTOR JOHN F. LUHRS Feb. 22, 1944. J, F, LUHRS 2,342,413

MEASURING AND CONTROLLING APPARATUS Filed Dec. 20, 1958 5 Sheets-Sheet 3 lNvENToR JOHN F. LUHRS Feb. 22, 1944. l` F, UHR5 2,342,413

MEASURING AND CONTROLLING APPARATUS Filed Dec. 20, 1938 5 Sheets-Sheet 4 F INVENTOR |6- 5 JOHN F. LuHRs fwwfmw Feb. 22, 1944. J, FI LUHRS MEASURING AND coNTRoLLING APPARATUS Filed Dec. 20. 1938 5 Sheets-Sheet 5 INVENTOR JOHN F. LUHRS Patented Feb. 22, 1944 MEASURING AND APPABA John F. Luhrs, Cievelan to Bailey Meter Co Delaware CONTROLLING TUS d Heights, Ohio, assignor mpany, a corporation of Application December 20, 1938, Serial No. 246.820

10 Claims.

This invention relates to the art of measuring and/or controlling the magnitude of a variable quantity, condition, relation, etc.,.a'nd particuiarly such a variable condition as the density oi' a liquid-vapor mixture, although the variable might 'be temperature, pressure, or any physical, chemicalI electrical, hydraulic, thermal, or other characteristic.

I have chosen to illustrate and describe as a preferred embodiment of my invention its adaptation .to the measuring and `controlling of the density and other characteristics of a flowing heated uid stream, such as the now of hydrocarbon oil through a cracking still.

While a partially satisfactory control of the cracking operation may be had from a knowledge of the temperature, pressure and rate of flow of the iiuid stream being treated, yet a knowledge of the density of the ilowing stream at different points in its path is of. a `considerably greater value to the operator.

In the treatment of water below the critical pressure, as in a vapor generator, a knowledge of temperature, pressure and rate of now may be sumcient for proper control, inasmuch as definite tables have been established for interrelation between temperature and pressure and from which tables the density of the liquid or vapor may be determined. However, there are no available tables for mixtures of liquid and vapor.

In the processing of a fluid. such as a petroleum hydrocarbon, a change in density of the iluid may occur through at least three causes:

i. The generation or formation oi vapor of the liquid, whether or not separation from the liquid occurs.

2. Liberation of dissolved or entrained gases.

Molecular rearrangement as by cracking or polymerization.

The result is that no temperature-pressuredensity tables maybe established for any liquid, vapor, or liquid-vapor conditionoi' such a fluid, and it is only through actualmeasurement of the density of a mixture of the liquid and vapor that the operator may have any -reliable knowledge as to the physical condition of the fluid stream at various points in its treatment.

It will be readily apparent to those skilled in `the art that the continuous determination of the density of such a flowing stream is of tremendous importance and value to an operator in controlling the heating, mean density, time oi detention `and/or treatment in a given portion of the circuit, ctc. A continuous knowledge'ot the density o1' such a heated flowing stream is' particularly ad vantageous where wide changes in density occur due to formation, generation, and/or liberation of gases, with a resulting formation oi.' liquidvapor mixtures, velocity changes, and varying time of detention in diil'erent portions of the fluid path. In fact, for a fixed or given volume of path, a determination oi' mean density in that portion provides a possibility of accurately determining the time that the iluid ln that portion of the path is subjected to heating or treatment. By my invention I provide the requisite system and apparatus wherein such information is made available continuously to an operator. and furthermore comprises the guiding means for automatic control of the process or treatment While illustrating and describingmy invention as preferably adapted to the cracking of petroleum hydrocarbon, it is to be understood that it may be equally adaptable to the vaporization or treatment oi' other fluids and in-other processes.

In the drawings:

Fig. 1 is a diagrammatic representation of density measuring apparatus for a heated fluid stream.

Fig. 2 is a detail oi' the mechanism illustrated in Fig. l.

Fig. 3 is a diagrammatic arrangement of the invention in connection with a heated iluld stream wherein mean density of the iluid in a portion of the path is determined.

Fig. 4 is a diagrammatic illustration of an embodiment oi' my invention wherein the time ci detention as well as time-temperature relation is determined.

Fig. 5 is a diagrammatic arrangement of the invention (similar to Fig. 3) wherein control arrangements are illustrated.

Plv. 6 is a diagrammatic arrangement of the invehtion (similar to Fig. 4) wherein control ai rangements are illustrated.

Referring now in particular to Fig. 1, I indicate a conduit I which may be considered as compris ing the once through iiuid path of an oil still wherein a portion of the path is heated as by a burner 2. The rate of ,ilow of the charge or relatively i untreated hydrocarbon is continuously measured by a volumetric type of ilow meter 3, while a similar volumetric ilow meter 4 is located with reference to the conduit I beyond the 'heat ing means or after the nowing iluid has been sub- `iected to heating or to other treatment or processing.

A control valve 69 is located in the conduit I whereby the rate oi' ilow of the fluid may be regu 55 lated. A control valve 68 located in the burner known capacity, and uid cannot pass through" without actuating the primary device;v The secondary element of such a meter usually is a counter withsuitably graduated dials for indicating the total quantity that has passed through the meter up to the time of reading. In the present invention, however, the rotatable shaft which normally actuates such a counter is adapt'- ed to drive or position the mechanism which functions to determine density of the fluid.

The primary elements 3 and 4 which are inv serted in the conduit I each have complemenmoment that the specific gravity or density of the fluid in the conduit I entering the meter 3 remains constant, then the density of the iuid passing through the meter 4 may be determined as follows: d4=da where ds=density ofjfluid passing through meter 3 :density of fluid passing through meter 4 Ss--speed of shaft 6 of meter 3 This is, of course, predicated upon the fact that the meters 3 and 4l are of the same size and design so that viii the same volume rate of fluid tary rotatable members! which are mounted for rotation upon shaft centers in such a manner as to be in sealing contact with the inner wall of the meter casing and with eachother. Thus, an effective seal is provided across the conduit I at device 3 and at device 4. However. in-

asmuch as the elements 5 are rotatable, pres-` at the Vsame density conditions is passing through the two,l then the speeds of the shafts 6 'I are thesame."

Asa practical means of mechanically solving the Formula 1 tofdet'ermine the density the density of the fluid passing through the meter 4, I will Vnow' describe indetail the showing of Figs. iaudz.v Y

A 'disk 8 is adapted to be rotated by the dis placement meter 3 through the shaft 6. FrictionallyL engagingthe disk 8 is a sphere or ball 9`likewisejfrictional1y engaging a rotatable spool primary element 3 varies directly with rate of fluid flow, directly with variations in speciilc volume of theuid, and inversely with variations in density of the fluid. The same is true of the speed of a shaft 1 leaving the primary element 4' in regard to the fluid flowing therethrough.

By interrelating or comparing the speed of the shafts 8, 'I I may determine the relative density between the two locations, or for example compare the density of the fluid before the heating means 2 with its density at a location after the heating means. This comparison will allow me to ascertain the change in specific volume or density, due to the treatment or heating by the means 2, as well as to ascertain an indication of the heat change in the fluid.

While I have stated that the speed of the shaft i as well as the speed of the shaft I will individually vary with rate of flow of the fluid, still if I am making a comparison of the speed of the shafts 6, 1 where the same fluid passes successively through the meters 3, d, then variations in rateof flow will have no more effect upon the one shaft speed than upon the other shaft speed, and may therefore be disregarded entirely. Thus the speed of the shafts 5, 1 will vary with variations in specific volume or density at the individual meters 3, 4.

As previously stated, for the example illustrated in Fig. 1, I consider that the fluid entering the meter 3 is the charge or relatively untreated hydrocarbon to the furnace, and at a substantially uniform specific gravity or density. Such may be determined periodically if desired to ascertain whether it has in fact departed from the design condition for which the meter 3 and shaft B are calibrated. Assuming then for the I0 supported bya carriage II. The spool I0 is provided with an arm I2 as shown in Fig. 2 carrying a pair of contacts I3 and I4 connected through suitable slip rings in a drum I5 supported by carriage II to opposed fields I6 and Il respectively of a motor I8.

The drum I5 is rotated by the meter 4 through the agency of the shaft 1 and carries a contact I9 cooperating with the contacts I3 I4. The contact I 9 'is connected through a slip` ring in the drum I5 directly to the power source 20 through a conductor 2L The arrangement is such that upon engagement of the contact I9 with the ,contact I3 the kfield I6 is energized andv conversely upon engagement of the contact I9 with the contact I4 the field II is energized. The motor I8 is adapted to drive an indicatingrecording pen arm 22 relative to a chart 23 through gears 24 and in unison therewith the carriage II through a gear 25 meshing with a suitable rack 25 carried in the carriage II.

In operation, assuming the system tobe in equilibrium, the contacts I3, I4 will be rotated at synchronous speed vwith the contact I9 so that the fields I6, I'I of the motor I8 are deenergized. Upon an increasein .the rate of firing through the burner 2 with a corresponding increase in specific volume and conversely a decrease in density of the. fluid passingthrough the meter 4, the speed of the shaft I will increase relative to the speed of the shaft 6. -Thusthe rotative speed of the drum I5 and of the contact` I9 willincrease relativeto the rotative speed of the disk 8, the spool I0 and the contacts I3, I4. The arrangement is such that thecontact I9 will engage the contact I3, causing energization ofthe field I6 and rotation of the motor I8 in proper direction to move the carriage II to the right on the drawings, whereby the radius of contact of the sphere 9 with the disk 8. relative to the center of the disk 8 will be increased, and. thereby the speed of rotationof the spool I0 and contacts I3, I4 will be increased` relative to what it was previously, and such actionfwill continue runtil the rotative speed of the contacts I3, I4 and the contact I9 is in synchronism and the contact I 9 is not close eircuited with either the contact I3 or the contact i4,

whereafter` rotation of the motor `I3 will cease. The position of the carriage `Il and correspondingiy (through the gear 24) of the indicator 22 relative to the chart 23 is indicative of the density of the fluid passing through the meter 4. This may be seen from the following:

Angular travel of |2= travel of BXRadius Angular travel of I3j=` travel of 1 But in equilibrium:

- Angular travel of I2=Angular travel of I9 'I'hereforetravel of 6 X Radius= travel of 1 R travel of 1 (2) travel of 6 and- When travel 6:0 lR=inflnity When V travel `1=Il R=0 Thus the radial 'distance from the center of the disk 8 to the point of contact of the sphere 9 with the disk 8, is a measure of the ratio of the speeds of the shafts 6, 1 and knowing the density of the fluid passing through the meter- 3, the said radius is a measure of the density ofthe fluid passing through the meter 4. The value of the density of the fluid passing through the meter 4 lis indicated and recorded relative to the chart 23 by the positioning of the winter 22 through the agency of the motor I8. r

From an observation of the value of densityAin dicated and recorded relative to the chart 23, I may so adjust the valve 68 and/or the valve 69 that optimum operating, treating, or processing may be attained.

Referring now to Fig. 3 wherein like parts bear the same reference numerals as in Figs. 1 and 2, I indicate that after the fluid is passed through the meter 4 it is .returned to a further heating section of the still, from which it passes through a .third displacement type meter 21 having an output shaft 28. The heating coil 29 will be hereinafter referred to as a first heating section, while the coil 30 will be referred to as a second heating section. In the preferredarrangement and operation of the still the section 30 is the conversion or cracking section and the one in whichitv is primarily desirable to continuously determine the mean density of the fluid, as well as its time of detention or treatment. For that reason I now desirably determine the mean density of the fluid in the section 3|! and accomplish this through an interrelation of the speeds of the meters 3, 4, 21 produced by the same weight flow passing successively through the meters.

The same total weight of fluid must pass through the three meters in succession so long as there is no addition toor diversion from the path intermediate the meters. It is equally apparent that in the heating of va, petroleum hydrocarbon as by the coil 29 between the meters 3 and 4, there will be a change in density of the fluid between the two meters, and furthermore that an additional heating ofthe fluid as by the coil 30 will further vary the density of the fluid as at the meter 21 relative t8 the meter 4.

Assume now that the conduit I is of a uniform size throughout and that the meters 3, 4, 21 are of the same size as well as' coeflicient or characteristic. The mean density of the fluid in the conversion section 3|! is then obtained by averaging the density of the fluid passing through the meters 4 and 21. A s for example:`

The density of the fluid passing through the meter 21 may be obtained in the same manner relative to the density of the fluid passing through the meter 3 as wasgpreviously determined for the density of the huid passing through the meter 4. Then simplifying this into a single operation I have:

'Ihus the mean density of the fluid in the conversion section 30 (knowing the density or speciflcv gravity of the fluid entering the system) may be directly computed from the speeds of the shafts l, 1, 28. l

In Fig. 3 I have shown mechanism similar to that of Figs. 1 and 2, whereby density of the fluid passing through the meter 4 is continuously indicated relative to the chart 23, while through a duplication of some of the parts cooperating with the disk -3 I continuously indicate the density of the fluid passing through the meter 21 upon the chart 3|. The arrangement illustrated wherein the two sets of mechanisms operate relative to the disk 3 at varying radii from thel center of the disk l is feasible, for it is not expected that either of the two mechanisms would ever have to go to azero radius or that the speed4 of the disk 8 would ever go to zero. At no time when the system is operating can there be zero flow through one of the meters.

With the density at the meter 4 indicated on lthe chart 23, and that at meter 21 on the chart 3|, I obtain the mean density through the conversion section lll through Formula 4 by averaging the positions of the gearing 24, 24' by means of a differential mechanism 32 which positions a pointer 33 relative to a chart 34 directly in terms of mean density mdao.

In Fig. 4 I illustrate a somewhat different ar rangement whereby I amlenabled to utilize the speed of the meters 4, 21 to determine the velocity and/or time of detention of the fluid within the heating portion. 30, and may also determine the time-temperature relation of` the conversion section of the still.

With the same fluid flowing successively through the meters 4, 21 the speeds of the shafts 6, `1 will vary only with variations in specific volume or density of the fluid.

path

However, the average speed of the shafts 6, 1 will vary as the rate of flow through the section 30 in cubic feet per unit of time. AX represents the cubic feet of fluid passing through meter 4 4 per minute and BY the cubic feet passing through meter 21. Then AX-l-BY 2 will equal the number of cubic feet of uid passing through the effective central location of section 30 or the average volume flow rate for the section. Since X=Y then equals the average volume ow rate. Thus the average speed of the shafts 6 and 1 is representative of the average volume rate of fluid ow through the section 30 in terms of cubic feet per unit of time. Knowing the cross-sectional area of the section 30, it is vapparent that the average volume flow rate in cubic feet per minute divided by the tube area in square feet will give the `aver-l age velocity of the fluid through the tube in terms of feet per minute. Knowing the length L of the path 34, it follows that any particle of fluid will theoretically take M minutes to travel the length L at a given average velocity. M is therefore the time of detention of a particle of fluid in the path 34 and the time during which it is subjected to treatment as by heating. Thus the average speed becomes directly proportional to a measure of time of detention or velocity. D To embody this portion1 of my invention in workable fashion I apply they angular movement of the shafts 6, 1 to an averaging gearing 35, from which a flexible shaft 36 is rotated at a speed the average of the speed of shafts 6 and l. To indicate or record such average speed an arm 31 is positioned by a motor 31A relative to an index 38 and a recording chart 39. The reversible motor 31A has opposed fields 40, 4| adapt ed to be energized-from a suitable source 42.

Energization of the field 40 for positioning the indicator 31 in one direction is effected through engagement of a contact arm 4t with a ccntact structure 44; and energization of the field` 4|' for positioning of the indicator 31 in opposite direction is effected through engagen-lentv of a contact arm 45 with the contact structure 45. When the fields 40 and 4l are simultaneously energized or deenergized the motor 31A is not urged to rotation.

The contact arm 43 is rotatably mounted on a fixed shaft 43 and is provided with a toothed hub 41 meshing with a pinion 5 5 driven by an extension oi thefflexible shaft 38. 43 is shown as being driven by the sli-aft B6 through a friction means 49 wherein the shaft 3B is actually broken but the two parte held in frictional engagement by means of a spring 5U, to the end that if the part of the sha'ft 36 connected to the pinion 43 is locked or heid against rotation the friction means will slip, allowing the gearing 35 to continue to rotate the shaft 3K5.

The arm 43 is periodically locked and held against rotation by means of a brake member 5| intermittently urged-against the hub 41 by a cam 52 rotated by a constant speed motor 53. The arrangement is such that the contact arm 43 is periodically, for constant increments of time, allowed to advance from an initial position in a counterclockwise direction, as shown in the drawings, and then locked against rotation by the shaft 36 through the agency of the brake member 5I. As the contact arm 43 isadvanced by the shaft 36 the periodic displacement from the initial posi- The pinion tion will be proportional to the speed of the shaft 36.

Subsequent to each advancement the contact arm 43 is returned to the initial position against the action of the brake member 5| by the contact structure 44 rotatably mounted on the shaft 46 and periodically oscillated by a cam 54 rotated by the motor 53. Upon engagement of the Contact structure 44 with the contact arm 43 the field 4l! will be energized to position the indicator 31 in one direction. Accordingly, so much of the apparatus as has been described will function to periodically position the pointer 31 in one direction by increments bearing a. functional relation to the speed of the shaft 36. Such positioning of the pointer 31 may be in direct proportion to the average speed of the meters 4, 21 or to the velocity or time of detention of the fluid flowing through the section 30. If desired, a functional relation may be embodied through rproper shaping of the cam 54, as will be understood bythose familiar with the art. y

The contact arm 45 is rotatably mounted on the shaft 46 and adaptedto be positioned by a cam 55 through a follower 56. The cam 55 is operated in unison with the indicator 31 by the motor 31A, and accordingly the contact arm 45 assumes a position in accordance with the position of the indicator 31. As the arm 45 is periodically moved by the contact structure 44 in returning the arm 43 to the initial position it is yieldably urgedk against the follower 56 and cam 55 by a spring 51. Engagement the contact structure 44 with the arm 45 eiects encrgization of the field 4I to position the indicator 31 in opposite direction to that caused by energization of the field 40. The contact structure 44 in periodically advancing to return the arms 43 and 45 to their initial position ineffect compares thev actual rate of speed of the 36 to that speed indicated or exhibited by the arm 31; and if the former has changed between such periodic advances, corrects the latter until they are again in agreement. So long as such agreement exists, no change is made in the position of the arm 31.v

The operation of the apparatus is cyclic and, assigning the parts to be in the position shown in Fig. 4, the contact arm 43 will advance from the initial -position in which it is shown for an increment of time'determined by the shape of the cam 52, which at the termination of the increment will urge the brake member 5I* against the hub 41. During the advance of the contact arm 43 the `contact structure 44 will remain stationary due to the shape of the cam 54. Likewise the contact arm 45 will remain stationary as the fields 40 and 4l of the motor 31A are both deenergized. Immediately subsequent to the advance of the contact arm 43 from the initial position the contact structure 44 will be rotated in a clockwise direction by the cam 54. Upon the contact structure 44 engaging the contact arm 45 the field 4 I of the motor 31A will be energized tending to position the indicator 31 in one direction. Likewise, upon the contact structure 44 engaging the contact arm 43 the field 40 will be energized tending to position the pointer 31 in opposite direction.

If the contact structure 44 engages the contact arms 43, 45 simultaneouslythe indicator 31 will remain stationary. If the contact arm 43 in its incremental advance is displaced beyond the contact arm 45, indicating that the actual speed of the shaft 36 is greater than that indicated by the pointer 31. engagement will take place between the contact structure 44 and contact arm 43 effecting energization of the field 40 and operating the pointer 31 to indicate an increase in speed. Simultaneously the contact `arm 45 will be positioned in proportion to the movement of thearm 31 in a counterclockwise direction through the cam 55 and follower 56. Positioning of the pointer 31.wi1l continue until the contact structure 44 engages the contact arm45, when both fields will be equally energized and the motor 31A not urged to rotation. Conversely, upon the speed of the shaft 36 decreasing, the contact arm 43 will not. advance to a position coincident with that oi' the contact arm 45, and accordingly the contact structure 44 will engage the contact arm 45 before engaging the contact arm 43. Such engagement will effect energization of the field 4| positioning the pointer 31 in a direction to indicate a decrease in the speed `of the shaft 36 and simultaneously positioning the contact arm 43 in a clockwise direction. Such positioning will continue until the contact structure 44 engages the contact arm 43, when both fields willbecome energized. Such incremental positioning of the arm 31 will continue during each cycle of operation until upon advancing the contact structure 44 simultaneously engages the contacts 43 and 45. The apparatus, therefore, functions to compare the actual speed of the shaft 36, as indicated by the angular position of the contact arm 43 at the termination of its incremental advance with the speed shown by the indicator 31; and then to periodically adjust the position of the arm 31 by increments proportional to the difference in angular position of the contact arms 43 and 45 until the showing of the indicator actual speed of the shaft 36.

After the contact structure 44 has returned the contact arm 43 to the initial position the shape of cam 54 permits the quick return of the contact structure 44 to the position shown in Fig. 4, thereby effecting substantially simultaneous deenergization of the fields 40 and 4|. The contact arm 45 follows the contact structure 44 in its quick return however until again engaging the cam follower 56. To avoid the possibility of a continuing energization of the field 4|, effecting a positioning of the arm 31, I show the fields 46 and 4| connected to the source 42 through a common connector 58. The circuit through the connector 56 is adapted to be broken by a switch 53 operated from the motor 53 at some predetermined point in the travel of the arms 43, 45 and contact structure 44 toward the initial position and to maintain the circuit openuntil the contact structure 44 has returned to the starting position, and is again starting to move toward the arms 43 and 45. Accordingly, regardiessof the fact that the contact arm 45 may remain in engagement with the contact structure 44 during a portion of its quick return, the field 4| will be deenergized and the indicator 31 remain stationary.

It will be observed that the arm 31 records on the chart 39 in terms of average speed of the meters 4, 21 or ln terms of time of detention of the fluid within the section 30,- or in terms of velocity of the fluid through the section 36.

I indicate at 60 the bulb of a gas-filled thermometer system, to which the Bourdon tube 62 is connected by the capillary 6|. The action is such that variations in temperature of the fluid passing through the conduit will be manifested by movement of the free end of the Bourdon tube 62 adapted to position a link 63.

31 agrees with thek The link 63 is pivotally connected to one end o1' a beam 65 carrying a recording pointer 66 adapted to record on the chart 61. The other end of the beam 65 is pivotally connected to a link 64 positioned by the motor 31A with the pointer 31 and therefore the` link 64 assumes a position representative of time of detention or velocity of the iiuid in the path 36. Assuming that the temperature remains constant and the Bourdon tube 62 stationary, then the beam 65 pivots around the lower end of the link 63 and the indicator 66 moves across the chart 61 directly according to time of detention. If, however, the temperature varies, then the beam 65 moves not only according to time, but according to temperature as well, and the record on the chart 61 is one of interrelation between time and temperature.

From an observation of the value of average speed of the meters 4, 21, or of time of detention of the fluid within the section 30, or of velocity of the fluid through the section 36. or of the time-temperature relation of the fluid, I may so adjust the valve 68 and/or the valve 63 that 4optimum operating treating, or processing may be attained.

In addition to the various records and indications of density, mean density, time of detention, and time-temperature relation, I contemplate that the movement of the various elements giving such indications or records may be adapted to actuate or position control devices effective in varying the rate of iiow of the iiuid or in controlling or varying `the treatment which, in the examples explained herein, is a. heating of the fluid.

Fig. 5, for example, is patterned after Fig. 3 but is additionally arranged so that the rate of supply of fluid to the treating system and/0r the rate of treatment may be automatically adjusted responsive to the value of density or mean density. Pointer 22 representative of density at meter 4 is arranged to position a pilot valve 12; pointer 16 representative 0f density at meter 21 is arranged to position a pilot valve 10; and pointer 33 representative of mean density through the conversion section 30 is arranged to position a pilot valve 1|. The pilot valves 10, 1|, 12 may be of the type disclosed and claimed in the Johnson Patent 2,054,464 and establish air loading pressures representative of the variable which is instrumental in positioning them. Such air loading pressures may be selectively applied to position the control valve 13 and/or the control valve 14 for regulating the rate of firing and/or the rate of now of nuid through the treating system. Hand actuated selective valves 15 are available so that the rate of supply of fluid may be controlled automatically by the regulating valve 14 selectively, either in accordance with density at' the inlet to the conversion section, or at the outlet of the conversion section, or from mean density through the conversion section. In like manner the hand valves 15 allow a selective actuation of the control valve 13 firing of the unit may be selectively under the control of density at the inlet to the conversion section, density at the outlet .from the conversion section, or mean density throught the conversion section.

Fig. 6 is patterned after Fig. 4, but is additionally arranged sc that the rate of supply of fluid to the treating system and/or the rate of treatment may be automatically adjusted responsive to the value of average speed of the meters whereby the rate of` I, 21, or of time of detention of the fluid within the section 30, or of velocity of the iluid through the section 30, or of the time-temperature relation ofthe iiuid being treated. The pointer 31 representative of velocity or time of detention is adapted to position the pilot valve 1.8 establishing a loading pressure representative thereof. The pointer 66 representative of time-temperature relation is adapted to position a pilot 111m accordance therewith.

The hand actuated valves 19 are provided so that the control valves 13, 14 may be selectively placed under the control of either the pilot'valve 11 or the pilot valve 1l. Thus the rate of flow of fluidl to be treated and/or the rate of treatment thereof may be automatically controlled responsive to variations in value of velocity, time of detention, or time-temperature relation of the iiuid undergoing treatment in the conversion section 30.

While I have chosen to illustrate and describe the functioning of my invention in connection with the heating of petroleum or hydrocarbon oil, it is to be understood that the method and apparatus is equally applicable to the treatment, process, or working of other fluids, such for example as in the vaporization of water to form steam.

While I have utilized density as representative of a condition change of a uid undergoing treatment, it is to be understood that there are other conditions which may vary with such treatment. Furthermore, that'by treatment I do not limit myself to the heating of a fluid, but that this may be a physical and/or chemical treatment resultng in a physical and/or chemical condition change. For example, I believe that the vaporization of water into steam is normally a physical condition change, whereas the treatment o hydrocarbon oil by cracking or polymerization is usually a combination of physical and chemical action. Furthermore, that there are undoubtedly many treatments or processes of iiuid which comprise merely a chemical change. In any event, I expect to be limited only as to the claims in view of prior art.

This application is a continuation-impart of my co-pending application SerialfNo. 152,856 filed in the United States Patent Oiiice July 9, 1937, and entitled Measuring and controlling apparatus, now Patent No. 2,217,638.

What I claim as new, and desire to secure by Letters Patent of the'United States, is:

I. Apparatus for continuously determining the time of detention of a flowing iiuid through a given portion of its path comprising in combination, a rotatable member at the inlet and at the outlet of said portion, means for imparting to said members an angular velocity proportional to the volume rate of iiow at the inlet and outlet respectively, means for determining the algebraic sum of said velocities, and an indicator positioned by said last named means.

2. Apparatus for indicating the time of detentionof a iiowing fluid in a processing zone comprising, means for rotating a iirst member in accordance with the velocity oi the iiuid entering said zone, means for rotating a second member in accordance with the velocity of the nuid leaving said zone, a differential mechanism actuated by said first and second members, and a third member positioned by said diierential mechanism in accordance with the average angular velocities of said first and second members.

3. Apparatus for determining the relationship between time of detention and temperature of a fluid owing through a processing zone comprising, means for rotating a first member in accordance with. the velocity of the fluid entering said zone, means for rotating a" second member in accordance with the velocity of the iiuid leaving said zone, a differential mechanism actuated by said first and second members, a third member positioned by said differential mechanism in accordance with the average angular velocities of said iirst and second members, means for determining the temperature of the fluid being processed, and an indicator under the joint control of said third member and said last named means.

4. Apparatusy for continuously determining the time of detention of a flowing iiuid through a given portion of its path comprising in combination, a displacement meter at the inlet 'of said portion, a member rotated by said meter at a velocity proportional to the existing volume rate of now, a second displacement meter at the outlet of said portion, a second member rotated at a velocity proportional to the existing volume rate of flow at said outlet, a differential mechanism actuated by said members, a third member rotated by said diierential mechanism at a` velocity proportional to the average velocity of said first two members, an indicator, and means for positioning said indicator in accordance with the velocity of said third member.

5. Apparatus for determining the time oi detention of a nowing fluid between a location in the iiow path remote from a reference point and the reference point and wherein the same weight rate of ilow exists at both said points, comprising in combination, a first `volumetric meter at the reference point, a second similar meter at said location, a shaft angularly moved by each of said meters and at a speed proportional to the flow through the respective meter, and means for continuously determining the average speed of said shafts.

6. Apparatus for controlling the processing of a ilowing iiuid undergoing condition change,

comprising in combination, heating means for the flow path, a first volumetric meter in the iiuid flow path ahead of the heated zone, a second volumetric meter in the iiuid iiow path after the heated zone, means continuously determining the average speed of said meters, and means in the flow path ahead of the heating zone and positioned by said determining means.

7. Apparatus for controlling the processing of a owing iiuid undergoing condition change, comprising in combination, heating means for the flow path, a iirst volumetric meter in the fluid ow path ahead of the heated zone, a-second volumetric meter in the fluid ow path after the heated zone, means continuously determining the average speed of said meters, and a regulating valve controlling the heating and positioned by said means.

8. Apparatus for controlling the processing of a iiowing fluid undergoing condition change, comprising in combination, heating means for the flow path, a rst volumetric meter in the iluid flow path ahead of the heated zone, a second volumetric meter in the fluid flow path after the heated zone, means continuously determining the average speed of said meters, means regulating the weight rate of ow of iiuid to be treated, and means `regulating `the heating, said last two named means jointly positioned by said first 11168118.

9. In the processing .of a uid owing under pressure through a substantially uniform cross section path without change in weight rate while in forced flow through the processing zone apparatus for determining the time of detention of the fluid in the processing zone comprising in combination, means for determlnin'g the velocity lof the fluid entering said zone, means for determining the velocity of the-fluid leaving said zone, and means connected to said velocity determining meansfor` continuously averaging said velocity determininations.

10. In the processing of a iiuid flowing under pressure through a substantially uniform cross section path without change in weight rate while in forcedow through the processing zone apparatus for determining the time of detention of the fluid in the processing zone comprising in combination, means for determining the volume flow rate of the fluid entering said zone, means for determining the volume now rate of the uid leaving said zone, and means for continuously averaging said volume ilow rate determinations.

` JOHN F. LUHRS. 

